Switches for connecting computers and various peripheral devices such as control terminals, display terminals, time generators, line printers, magnetic tapes, magnetic discs, and the like are well known in the communication arts. Typical switching requirements for communications systems require that a plurality of lines associated with one device be interconnected to a plurality of lines associated with another device, these lines generally being of the type that carry parallel, digital data either in binary or BCD format. A typical crossbar switching matrix includes a plurality of X ports and a plurality of Y ports. Each port has a plurality of associated lines. Each X-Y port intersection has an associated X-Y intersection or control latch and a plurality of associated switching planes so that all the lines associated with the X port and the Y port defining the X-Y intersection latch are interconnected.
Prior art switches for effecting this type of switching have been generally mechanical, large in size, costly, and require elaborate control circuitry. Attempts have been made to design solid state switches using back-to-back connections of moderately efficient digital multiplexer and demultiplexer circuits. For bi-directional traffic, each set had to be duplicated. Such switches show little improvement over mechanical switches, the improvement gain being mostly derived from the fact that the return wire for a signal wire need not be switched as the signal was reconstituted electronically. In mechanical switches, the return wire needs to be switched in order to maintain ground integrity.
As a result of recent developments in analog switching arrays with memory and digital control circuits, it has become feasible to design large switching matrices using solid state circuitry. However, as the number of lines to be switched increases, control circuitry and status determination circuitry for the switching matrix has become increasingly complex. The control system disclosed herein solves many of the above problems by providing relatively simple control circuitry that accomplishes a plurality of related control functions through time sharing of various control elements.